Answers to Written Lab 3
181
Answers to Written Lab 3
1.
172.16.10.5 255.255.255.128: Subnet is 172.16.10.0, broadcast is
172.16.10.127, and valid host range is 172.16.10.1 through 126.
You need to ask yourself, "Is the subnet bit in the fourth octet on or
off?" If the host address has a value of less than 128 in the fourth octet,
then the subnet bit must be off. If the value of the fourth octet is higher
than 128, then the subnet bit must be on. In this case, the host address
is 10.5, and the bit in the fourth octet must be off. The subnet must be
172.16.10.0.
2.
172.16.10.33 255.255.255.224: Subnet is 172.16.10.32, broadcast is
172.16.10.63, and valid host range is 172.16.10.33 through 10.62.
256
- 224 = 32. 32 + 32 = 64--bingo. The subnet is 10.32, and the
next subnet is 10.64, so the broadcast address must be 10.63.
3.
172.16.10.65 255.255.255.192: Subnet is 172.16.10.64, broadcast
is 172.16.10.127, and valid host range is 172.16.10.65 through
172.16.10.126.
256
- 192 = 64. 64 + 64 = 128, so the network address must be
172.16.10.64, with a broadcast of 172.16.10.127.
4.
172.16.10.17 255.255.255.252: Subnet is 172.16.10.16, broadcast is
172.16.10.19, and valid hosts are 172.16.10.17 and 18.
256
- 252 = 4. 4 + 4 = 8, plus 4 = 12, plus 4 = 16, plus 4 = 20--bingo.
The subnet is 172.16.10.16, and the broadcast must be 10.19.
5.
172.16.10.33 255.255.255.240: Subnet is 172.16.10.32, broadcast is
172.16.10.47, and valid host range is 172.16.10.33 through 46.
256
- 240 = 16. 16 + 16 = 32, plus 16 = 48. Subnet is 172.16.10.32;
broadcast is 172.16.10.47.
6.
192.168.100.25 255.255.255.252: Subnet is 192.168.100.24, broad-
cast is 192.168.100.27, and valid hosts are 192.168.100.25 and 26.
256
- 252 = 4. 4 + 4 = 8, plus 4 = 12, plus 4 = 16, plus 4 = 20, plus 4 =
24, plus 4
= 28. Subnet is 100.24; broadcast is 100.27.
Copyright ©2002 SYBEX, Inc., Alameda, CA
www.sybex.com